Surface tension is a property exhibited by the surface of liquids. It arises due to the cohesive forces between molecules. When molecules of liquids are not totally surrounded by other molecules of the liquid itself they tend to get attracted to molecules of other materials around them. Surface tension is defined in units of force per unit length or N/m.

Surface tension is what attracts molecules of liquids to form drops, it allows light objects to float on the surface of liquids, and insects to walk on water, it creates a layer of separation between substances that are not similar like oil and water.